1. Field of the Invention
The present invention relates to a deflection yoke for Braun tube, and more particularly, to a deflection yoke for Braun tube having a pair of horizontal deflection coil and a vertical deflection coil formed in a half-muscle type in which the height of a first neck flange coil of the horizontal deflection coil and the length of a main deflection part coil are in a predetermined ratio for the length of a second neck flange coil, to thereby optimize a neck shadow and improve a deflection sensitivity and a screen adjustment characteristic (Integrated Tube Component).
2. Description of the Background Art
FIG. 1 is a schematic sectional view showing internal structure of a general Braun tube in accordance with a conventional art.
As shown in the drawing, a general Braun tube includes an electron gun 4 for discharging three electron beams 7, a screen 1 on which the electron beams 7 hit to produce an image, a shadow mask 2 for discriminating the three electron beams 7, a deflection yoke 3 for deflecting the electron beams onto a predetermined fluorescent face of the screen 1.
Reference numeral 5 denotes a panel, 6a denotes a screen unit of a funnel, and 6b denotes a neck part of the funnel.
Thusly constructed Braun tube performs a function to receive an electric signal for a picture from an external source and change it to a light signal so as to be displayed as a picture having functions of a position and a content (color) on the fluorescent face of the screen.
Accordingly, the content signal having information on the color of the picture displayed on the screen is applied to the electron gun 4, and a color combination of a red (R) electron beam, a green (G) electron beam and a blue (B) electron beam is appropriately made to display a desired color on the screen.
The content signal of the picture is applied to the deflection yoke 3, so that the position point of the screen which the R, G and B electron beams radiated from the electron gun 4 reach is adjusted to display a desired picture.
FIG. 2 shows a detailed view of the deflection yoke. As shown in the drawing, the deflection yoke 3 includes a horizontal deflection coil 31 for horizontally deflecting the electron beam radiated from the electron gun 4 installed in Braun tube, a vertical deflection coil 33 for vertically deflecting the electron beam the electron beam, a conical ferrite core 34 for reducing the loss of a magnetic force generated from the horizontal deflection coil 31 and the vertical deflection coil 33, to heighten magnetization efficiency, and a holder 32 for fixing the horizontal and vertical deflection coils 31 and 33 and the ferrite core 34 at a determined position and for insulating the horizontal deflection coil 31 and the vertical deflection coil 33.
After the thusly constructed deflection yoke 3 is mounted at the neck part, when current is applied to the horizontal deflection coil and the vertical deflection coil, a desired picture is displayed on the screen.
The operation of the general deflection yoke 3 constructed as described above will now be explained.
Generally, current having a frequency of 15.75 KHz or more flows to the horizontal deflection coil 31 of the deflection yoke, to generate a magnetic field. By using the magnetic field, the electron beams inside Braun tube are deflected in the horizontal direction.
Likewise, current which usually has a frequency of 50 Hz flows to the vertical deflection coil 33, to generate a magnetic field. By using the magnetic field, the electron beams are deflected in a vertical direction.
Recently, a self-convergence type deflection yoke has been developed in which, by virtue of a nonuniform magnetic field according to the horizontal deflection coil 31 and the vertical deflection coil 33, the three electron beams can make a convergence on the screen even without any supplementary circuit or any supplementary unit.
That is, the winding distributions of the horizontal deflection coil 31 and of the vertical deflection coil 33 are adjusted to generate a barrel type magnetic field or a pin-cushion type magnetic field by regions (i.e., an opening part (a screen flange unit), a middle part or a neck part, etc). Thus, the three electron beams have different deflection forces each other, so that the electron beams can be converged into the same point in different distances from the starting positions of the electron beams to the screen 1, the reaching position.
In the case that current flows to the horizontal and vertical deflection coils 31 and 33 to generate a magnetic field, since it is difficult to deflect the electron beams onto the entire surface of the screen only with the magnetic field according to the horizontal and vertical deflection coils 31 and 33, the ferrite core 34 of high permeability is used to minimize the loss on the return path of the magnetic field, thereby heightening the efficiency of the magnetic field and thus increasing the magnetic force.
Also, in order to heighten the deflection sensitivity, generally, the deflection coil is moved toward the electron gun. In this case, however, a problem arises that the neck shadow (a region formed in order for the deflected electron beam to hit the funnel portion to thereby prevent the electron beam from reaching the screen) is shortened.
Reversely, in case that the deflection coil is moved toward the screen to obtain a sufficient space for the neck shadow, since the deflection sensitivity representing a capability in deflecting the entire screen is deteriorated due to a constant amount of current applied from an external source. Thus, in this case, more current needs to flow thereto.
Accordingly, the deflection sensitivity and the neck shadow are hardly compatible. In an effort to solve the problem, there has been proposed a coil winding type of a half muscle type coil, that is, a medium type between the flange type coil and the muscle type coil.
FIGS. 3A and 3B are perspective view showing a flange type coil and a muscle type coil in accordance with the conventional art.
As shown in FIG. 3A, in case of the flange type coil, once the length and a position are determined in a simulation, a complementing coverage to complement it during designing is very limited.
For example, a method for complementing the deflection sensitivity during designing exists merely to make an electrically connected state. Actually, in order to complement the deflection sensitivity, the flanges 31a and 31b, portions where a magnetic field for making deflection is not almost generated, and especially, the flange 31a of the opening, are to be minimized and the position of a main deflection portion coil 31d, that is, the portion which generates a main deflection magnetic field is to be complemented.
However, in this case, since the form of a frame mechanically configuring the flange type coil should be changed, it is very difficult to complement it during designing.
Meanwhile, in case of the muscle type coil, as shown in FIG. 3B, unlike the flange type coil, it doesn""t have a flange at the neck portion, so that the position of a window can be adjusted to control the sensitivity to a level and adjust the neck shadow. However, it is disadvantageous in that the overall length of the deflection yoke coil is changed due to the basic form size and position, limiting its designing operation for an optimum setting.
FIG. 4 is a perspective view of a general half-muscle type deflection coil in accordance with the conventional art, FIGS. 5A though 5C are respectively a front view, a side view and a plan view of the general half-muscle type deflection coil in accordance with the conventional art, and FIG. 6 is a view showing a pattern of a misconvergence of a screen according to a deflection coil in accordance with the conventional art.
As shown in the drawings, the half-muscle type horizontal deflection coil 31 or the half-muscle type vertical deflection coil 33 have a form that can suitably optimize the deflection sensitivity and the neck shadow. The half-muscle type coil includes an opening flange coil 31a, a first neck flange coil 31b having a flange, a second neck flange coil 31c formed in a horizontal direction, and a main deflection portion coil 31d connecting the opening flange coil 31a and the first neck flange coil 31b. 
In this respect, when the pair of horizontal and vertical deflection coils 31 and 33 fabricated as described above are combined to face each other and current is applied thereto to proceed a screen adjustment of Braun tube, the following problems arise.
That is, generally, Braun tube and the deflection yoke has an error in its fabrication, and due to various factors such as allowances of elements themselves in initial fabrication to be used for Braun tube and assembly allowances between the elements, there occurs asymmetry between an xe2x80x98Rxe2x80x99 beam and a xe2x80x98Bxe2x80x99 beam, as shown in FIG. 6. Thus, in order to solve the asymmetry, a magnetic material is typically attached to the neck portion of the deflection yoke.
However, as for the half-muscle type horizontal deflection coil 31, in order to obtain the length of the neck shadow, in case that the length xe2x80x98Ixe2x80x99 of the second neck flange coil is extended to the screen, the height (vertical width) xe2x80x98hxe2x80x99 of the first neck flange coil is lowered down, causing a problem that the leakage magnetic field due to the first neck flange coil of the deflection yoke is reduced.
Accordingly, as the leakage magnetic field is reduced, even when a bar-type magnetic material is attached as in the conventional art, the asymmetry between the xe2x80x98Rxe2x80x99 beam and the xe2x80x98Bxe2x80x99 beam generated on the screen is hardly controlled.
Therefore, an object of the present invention is to provide a deflection yoke for Braun tube suitable to have a good adjustment when the deflection yoke and Braun tube are in an ITC (Integrated Tube Components) procedure, improve a deflection sensitivity and optimize the characteristics of a neck shadow.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a deflection yoke for Braun tube having a horizontal deflection coil including: an opening flange coil; a main deflection portion coil extended with a predetermined length from the both end portions of the opening flange coil backwardly; a first neck flange coil connected to the extended end portions of the main deflection portion coil; and a second neck flange coil formed at the front side of the first neck flange coil, wherein, assuming that the height of the first neck flange coil is xe2x80x98hxe2x80x99, the length of the second neck flange coil is xe2x80x98Ixe2x80x99 and their ratio (I/h) is xe2x80x98Axe2x80x99, xe2x80x98Axe2x80x99 is greater than 0.5 and smaller than 2.0.
To achieve the above objects, there is also provided a deflection yoke for Braun tube having a horizontal deflection coil including: an opening flange coil; a main deflection portion coil extended with a predetermined length from the both end portions of the opening flange coil backwardly; a first neck flange coil connected to the extended end portions of the main deflection portion coil; and a second neck flange coil formed at the front side of the first neck flange coil, wherein, assuming that the length of the main deflection portion coil is xe2x80x98Lxe2x80x99, the length of the second neck flange coil is xe2x80x98Ixe2x80x99 and their ratio (I/L) is xe2x80x98Bxe2x80x99, xe2x80x98Bxe2x80x99 is greater than 0.04 and smaller than 0.24.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
FIG. 1 is a schematic view showing internal structure of a general Braun tube in accordance with a conventional art;
FIG. 2 is a schematic view of a general deflection yoke in accordance with the conventional art;
FIGS. 3A and 3B are perspective view of a flange type coil and a muscle type coil in accordance with the conventional art;
FIG. 4 is a perspective view of a general half-muscle type deflection coil in accordance with the conventional art;
FIGS. 5A though 5C are respectively a front view, a side view and a plan view of the general half-muscle type deflection coil in accordance with the conventional art;
FIG. 6 is a view showing a pattern of a misconvergence of a screen according to a deflection coil in accordance with the conventional art;
FIGS. 7A though 7C are respectively a front view, a side view and a plan view of a half-muscle type deflection coil in accordance with the present invention; and
FIG. 8 shows a pattern according to a deflection coil adopted to the deflection yoke in accordance with the present invention.